A power semiconductor device having a metal block for heat dissipation (heat spreader) mounted on an insulating sheet, and a semiconductor element set on the metal block, for example, as disclosed in Patent Literature 1 shown below, is known. A power semiconductor device of this kind incorporates a power semiconductor element such as an IGBT.
In the power semiconductor device described in Patent Literature 1, the insulating sheet is made slightly larger than the metal block such as to jut out from edges of the metal block to a certain size. The insulating sheet thus provided is bent into a region on the metal block side. Further, an encapsulation resin is provided so as to cover a back surface portion of the bent insulating sheet. This construction enables securing a creeping distance so that the insulation with the insulating sheet is secured. A reduction in size of the semiconductor package can also be achieved by bending the insulating sheet.
A semiconductor device incorporating a power semiconductor element uses a large amount of power. A high insulating effect is therefore required in the package structure for the semiconductor device. A study has also been made about this point in the above-mentioned related art, and the development of techniques for securing insulation in semiconductor devices incorporating power semiconductor elements is being pursued.